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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 595 records · Page 33Linked to original sources
USGS1955

Pegmatites of the Middletown area, Connecticut

The pegmatites of the Middletown area in Connecticut have been mined almost continuously for feldspar and muscovite mica since about 1865, Pegmatites in this and other areas have recently become the subject of renewed interest because pegmatites are the potential source of beryl, the ore mineral of beryllium. During 1948 to 1950, the Geological Survey studied and mapped the pegmatites in an area of about 58 square miles near Middletown. The primary objectives of the mapping were to determine beryllium resources of the Middletown area, and to ascertain relationships of beryl-bearing pegmatites to non-beryl-bearing pegmatites and to type of wall rock.

Connecticut↗
USGS1957

Reconnaissance of the water resources of the Lonesome Valley area, Yavapai County, Arizona

In accordance with a request from its cooperating agency, the Arizona State Land Department, the U.S. Geological Survey has made a brief reconnaissance of the water resources of the Lonesome Valley area, Yavapai County, Ariz., to determine the probable hydrologic effects of a proposed dam on Lynx Creek. The construction of this dam has been proposed by the Arizona Game and Fish Department, for recreational and fish-cultural purposes. Data on the geology of the area were furnished by Mrs. Medora M. Krieger, geologist, Geologic Division, U.S. Geological Survey, and the map was prepared by Floyd R. Twenter, geologist, Ground Water Branch.

Arizona↗
USGS1978

Principal facts for gravity stations in and adjacent to the Superstition Mountains, Gila, Pinal, and Maricopa counties, Arizona

A gravity survey was made in the Superstition Mountains in Gila, Pinal, and Maricopa Counties during November 1976 as part of a wilderness study being conducted by the U.S. Geological Survey and the U.S. Bureau of Mines. The purpose of the survey was to map buried structural boundaries and features (e.g. caldera margins) that are important in assessing the mineral potential of the area.

Arizona↗
USGS1980

Seismic hazard study of the western portion of the Garlock fault [California]

Investigations of the western segment of the Garlock fault were conducted at Castac Lake, Twin Lakes and Oak Creek Canyon. Studies were concentrated on the youngest fault trace as delineated by Clark (1973). Seismic refraction surveys, topographic surveys and geologic mapping provided positive evidence for fault offsets in Quaternary deposits at Twin Lakes and Oak Creek Canyon. Investigations at Castac Lake were concentrated on the fault segment north of the lake. Previous investigations south of the lake and across the dry lake bottom exposed unbroken strata dating back 8050 +300 years B.P. No evidence of offset of young deposits was found north of the lake from surface investigations or seismic refraction data. Trenching of sag pond deposits at Twin Lakes revealed fault traces representing 2 events confined to a zone 3 meters wide. The stratigraphy at Twin Lakes consists of alternating units of clay and sand allowing measurements of vertical offsets. Based on radiocarbon dates of detrital charcoal, the most recent movement occurred less than 890 +195 years B.P. and the proceeding event occurred greater than 2,800 +165 years B.P. Total vertical offset was 80 to 100 cm for the most recent movement and 55-60 cm for the proceeding event. Geomorphic analysis of offset alluvial stream channels at Oak Creek Canyon provided an estimate of 1.6 to 3.3 mm per year of left lateral movement during Holocene and late Pleistocene times. This estimate is based on correlation of soil profile development with dated soil stratigraphy in the San Joaquin Valley. Scarp heights and lack of definitive evidence for recent left-lateral offset in Oak Creek Canyon indicates a significant and perhaps predominant vertical component of movement with: 1) a comparatively long recurrence interval and/or 2) a small component of left-lateral movement. Arching of late Pleistocene deposits in Oak Creek Canyon is consistent with right-lateral rather than left-lateral wrench faulting, suggesting a fluctuation in stresses along this part of the fault since late Pleistocene time.

Open-File Report↗
USGS1983

Assessment of gray whale feeding grounds and sea floor interaction in the northeastern Bering Sea

A dense ampeliscid amphipod community in Chirikov Basin and around St. Lawrence Island in the northeastern Bering Sea has been outlined by summarizing biological studies, analyzing bioturbation in sediment samples, and examining sea floor photos and videotapes. The amphipod population is associated with a homogeneous, relict fine-grained sand body 0.10-1.5 m thick that is deposited during the marine transgression over the Bering land bridge 8,000-10,000 yr B.P. Modern current and water mass movements and perhaps whale feeding activity prevent modern deposition in this area. The distribution of the transgressive sand sheet, associated amphipod community and feeding gray whales mapped by aerial survey correlate closely with three types of sea-floor pits observed on high (500 kHz) and low (105 kHz) resolution side-scan sonar; they are attributed to gray whale feeding traces and their subsequent current scour modification. The fresh and modified feeding pits are present in 22,000 km2 of the basin and they cover a total of 2 to 18% of the sea floor in different areas of the feeding region. The smallest size class of pits approximates whale mouth gape size and is assumed to represent fresh whale feeding pits. Fresh feeding disturbance of the sea floor is estimated to average about 5.7% for a full feeding season. Combined with information that 34% of the measured benthic biomass is amphipod prey species, and calculating the number of gray whale feeding days in the Alaskan waters plus amount consumed per day, it can be estimated that Chirikov Basin, 2% of the feeding area, supplies a minimum of 5.3 to 7.1% of the gray whale's food resource in the Bering Sea and Arctic Ocean. If a maximum of 50% of the fresh feeding features are assumed to be missed because they parallel side-scan beam paths, then a maximum whale food resource of 14.2% is possible in northeastern Bering Sea. Because of side-scan techniques and possible higher amphipod biomass estimates, a reasonable minimum estimate of the total whale food resource in northeastern Bering Sea is 10%. These data show that side-scan sonar is a powerful new technique for analyzing marine mammal benthic feeding grounds. Sonographs reveal that the gray whales profoundly disturb the substrate and initiate substantial further erosion by bottom currents, all of which enhances productivity of the prey species and results in a 'farming of the sea floor'. In turn, because of the high concentration of whale prey species in a prime feeding ground that is vulnerable to the development of petroleum and mining for sand, great care is required in the exploitation of these resources in the Chirikov Basin.

Open-File Report↗
USGS1987

Single-channel seismic-reflection profiles collected aboard R/V POWELL, cruises P-2-85, P-3-85, P-4-85 in the nearshore waters around Puerto Rico and the Virgin Islands

Approximately 4,600 nmi (8,519 km) of single-channel seismic-reflection data were collected in the nearshore waters around Puerto Rico and the Virgin Islands simultaneously, but on a noninterference basis, with a gravity program funded by the Defense Mapping Agency. The survey was conducted on cruises P-2-85, P-3-85, and P-4-85 of the R/V POWELL between February 28 and April 8, 1985. Seismic instrumentation included two 40 in 3 (755 cm 3 ) airguns and a 200-ft (60-m) single-channel hydrophone streamer. In addition, a Uniboom sled and 8-ft (2.4-m) single-channel hydrophone streamer were used in water depths less than 660 ft (200 m). Navigation control was provided by a Magnavox Integrated Navigation System which integrates data from Global Positioning System (GPS) satellites, transit satellites, bottom-track sonar, Loran-C, Mini-Ranger stations, gyrocompass and speed log. GPS provided the most accurate navigational control, but was functional for only about 12 hours each day. The transit satellite system operated throughout the cruise and provided relatively accurate positions when GPS was not operational. The Mini-Ranger stations proved to be unreliable because of problems at the shore stations and Loran-C operated only on the north side of the islands, at times in only the range-range mode. Because the gravity program required accurate data and strict navigation control, some lines had to be run more than once or run with a following sea in a westerly direction only. Consequently, there is tight line spacing in some areas. The Uniboom high-resolution reflection data are good to poor in the shelf areas around Puerto Rico but are generally poor over the predominantly carbonate sediments around the Virgin Islands. The airgun data are fair to good, particularly considering the ship cruised at about 7 kn (13.0 km/hr) and at times reached 8 kn (14.8 km/hr) which is about the upper limit at which the system will function. Original seismic profile records can be seen at the U.S. Geological Survey offices, Woods Hole, MA 02543. Microfilm copies of the seismic profile records and trackchart can be purchased only from the National Geophysical Data Center, Code E64, 325 Broadway, Boulder, CO 80303 (303/497-6345).

Open-File Report↗
USGS1996

Bibliography of selected water-resources publications on Nevada by the U.S. Geological Survey, 1885 through 1995

References to 898 water-resources publications are listed alphabetically by senior author and indexed by hydrographic-area name or other geographic features. Most of the publications were written between 1960 and 1995 by U.S. Geological Survey scientists and engineers of the Water Resources Division, Nevada District. Also included are references to publications by other Water Resources Division authors that deal with Nevada hydrology. References to publications written before 1960 are included to provide a historical perspective. The references include several types of Geological Survey book and map publications, as well as State-series reports, journal articles, conference and symposium papers, abstracts, and graduate- degree theses. Information on publication availability is provided also.

Open-File Report↗
USGS2014

Geologic cross section D-D' through the Appalachian basin from the Findlay arch, Sandusky County, Ohio, to the Valley and Ridge province, Hardy County, West Virginia

This chapter is a re-release of U.S. Geological Survey Scientific Investigations Map 3067, of the same title, by Ryder and others (2009). For this chapter, two appendixes have been added that do not appear with the original version. Appendix A provides Log ASCII Standard (LAS) files for each drill hole along cross-section D-D' ; they are text files which encode gamma-ray, neutron, density, and other logs that can be used by most well-logging software. Appendix B provides graphic well-log traces and lithologic descriptions with formation tops from each drill hole.

Appalachian basin↗
USGS2014

Geologic cross section E-E' through the Appalachian basin from the Findlay arch, Wood County, Ohio, to the Valley and Ridge province, Pendleton County, West Virginia

This chapter is a re-release of U.S. Geological Survey Scientific Investigations Map 2985, of the same title, by Ryder and others (2008). For this chapter, two appendixes have been added that do not appear with the original version. Appendix A provides Log ASCII Standard (LAS) files for each drill hole along cross-section E–E' ; they are text files which encode gamma-ray, neutron, density, and other logs that can be used by most well-logging software. Appendix B provides graphic well-log traces from each drill hole.

Appalachian basin↗
USGS2014

Regional seismic lines across the Rome trough and Allegheny Plateau of northern West Virginia, western Maryland, and southwestern West Virginia

This chapter is a re-release of U.S. Geological Survey Geologic Investigations Map I–2791, of the same title, by Kulander and Ryder (2005), which in printed form consists of two oversized sheets and an accompanying pamphlet. The digital version of this publication, however, is only available as the pamphlet and a collection of all the individual graphics that are found on the two sheets.

Appalachian basin, Rome Trough↗
USGS2008

Geology of the Southern Appalachian Mountains

The Southern Appalachian Mountains includes the Blue Ridge province and parts of four other physiographic provinces. The Blue Ridge physiographic province is a high, mountainous area bounded by several named mountain ranges (including the Unaka Mountains and the Great Smoky Mountains) to the northwest, and the Blue Ridge Mountains to the southeast. Metamorphic rocks of the mountains include (1) fragments of a billion-year-old supercontinent, (2) thick sequences of sedimentary rock that were deposited in subsiding (sinking) basins on the continent, (3) sedimentary and volcanic rocks that were deposited on the sea floor, and (4) fragments of oceanic crust. Most of the rocks formed as sediments or volcanic rocks on ocean floors, islands, and continental plates; igneous rocks formed when crustal plates collided, beginning about 450 million years ago. The collision between the ancestral North American and African continental plates ended about 270 million years ago. Then, the continents began to be stretched, which caused fractures to open in places throughout the crust; these fractures were later filled with sediment. This product (U.S. Geological Survey Scientific Investigations Map 2830) consists of a geologic map of the Southern Appalachian Mountains overlain on a shaded-relief background. The map area includes parts of southern Virginia, eastern West Virginia and Tennessee, western North and South Carolina, northern Georgia and northeastern Alabama. Photographs of localities where geologic features of interest can be seen accompany the map. Diagrams show how the movement of continental plates over many millions of years affected the landscapes seen today, show how folds and faults form, describe important mineral resources of the region, and illustrate geologic time. This two-sided map is folded into a convenient size (5x9.4 inches) for use in the field. The target audience is high school to college earth science and geology teachers and students; staffs of educational and interpretive programs within Federal, State, and private agencies; and tourists and residents of the Southern Appalachian region who want to know more about the area. The map is companion to the DVD, 'The Southern Appalachians, a Changing World' (http://pubs.usgs.gov/gip/so_app/) and the Teacher's Guide and brochure, 'Birth of the Mountains' (http://pubs.usgs.gov/gip/birth). The map shows the location of sites that are featured in these publications.

Scientific Investigations Map↗
USGS2014

Bathymetry of the waters surrounding the Elizabeth Islands, Massachusetts

The Elizabeth Islands in Massachusetts that separate Vineyard Sound from Buzzards Bay are the remnants of a moraine (unconsolidated glacial sediment deposited at an ice sheet margin; Oldale and O’Hara, 1984). The most recent glacial ice retreat in this region occurred between 25,000 and 20,000 years ago, and the subsequent rise in sea level that followed deglaciation caused differences in the seafloor character between Buzzards Bay and Vineyard Sound. The relatively rough seafloor of Vineyard Sound reflects widespread exposure of glacial material. Shoals mark the location of recessional ice contact material, and deep channels illustrate where meltwater drainage incised glacial deposits. Following ice retreat from the Elizabeth Islands, a glacial lake formed across the mouth of Buzzards Bay, when the lake drained, it scoured two deep channels at the southern end of the bay. Sea level rise began to inundate Vineyard Sound and Buzzards Bay about 8,000 years ago and continues to modify the modern seafloor (Robb and Oldale, 1977). Fine-grained marine and estuarine sediments were deposited in the partially protected setting of Buzzards Bay. These deposits, up to 10 meters in thickness, buried the high-relief glacial landscape and created the generally smooth modern seafloor. In contrast, the Vineyard Sound of today experiences strong tidal currents, which largely prevent the deposition of fine-grained material and constantly rework the glacial sand and gravel within shoals. The seafloor of the sound largely reflects the contours of the ancient glaciated landscape that existed before sea level began to rise. The bathymetric data used to create the hillshaded relief image of the seafloor were collected by the U.S. Geological Survey (USGS) in cooperation with the Massachusetts Office of Coastal Zone Management and supplemented with National Oceanic and Atmospheric Administration hydrographic survey data. The map shows the detailed bathymetry of Buzzards Bay and Vineyard Sound with depth soundings shown on a 5-meter-per-pixel grid. Depths are coded by color where the deepest areas are in blue and the shallowest areas are in orange. The aerial photography for the Elizabeth Islands and Massachusetts mainland were obtained from the Massachusetts Office of Geographic Information. Data collected during this statewide cooperative project have been released in a series of USGS open-file reports. These publications and information regarding geologic mapping in Massachusetts can be obtained from the Coastal and Marine Geology Program’s Web site (http://woodshole.er.usgs.gov/project-pages/coastal_mass/).

Massachusetts↗
USGS2020

Predicted pH of groundwater in the Mississippi River Valley alluvial and Claiborne aquifers, south-central United States

Regional aquifers in the Mississippi embayment are the principal sources of water used for public and domestic supply, irrigation, and industrial uses throughout the region. An understanding of how water quality varies spatially, temporally, and with depth are critical aspects to ensuring long-term sustainable use of these resources. A boosted regression tree (BRT) model was used by the U.S. Geological Survey (USGS) to map water quality in the three regional aquifers with the largest groundwater withdrawals in the embayment: the Mississippi River Valley alluvial (MRVA) aquifer, middle Claiborne aquifer (MCAQ), and lower Claiborne aquifer (LCAQ). The BRT model was used to predict pH to 1-kilometer raster grid cells for seven aquifer layers (one MRVA, four MCAQ, two LCAQ) following the hydrogeologic framework of the Mississippi embayment aquifer system regional MODFLOW model. The methods and approach used for pH predictions are the same as those used recently by the USGS to predict specific conductance and chloride in the aquifers. Explanatory variables for the BRT models included variables describing well location and construction, surficial variables such as soil properties and land use, and variables extracted from the groundwater flow model, such as groundwater levels and ages. The primary source of pH data was the USGS National Water Information System database. Additional data from State ambient groundwater monitoring programs and the Safe Drinking Water Information System also were used. For wells sampled multiple times, the most recent sample was used. Because groundwater residence times are long (greater than 100 years) throughout much of the study area, the possible effects of changes in water quality over time were considered small compared to the improvement in overall model accuracy by using available historical data. Values of pH from 3,362 wells for samples collected between 1960 and 2018 were used as training data for the BRT model. An additional 839 samples were used as holdout data to evaluate model performance. The predictive performance of the pH model is lower than for the training dataset, as indicated by an r-squared value of 0.89 for the training data and an r-squared of 0.71 for the holdout data. The root mean squared errors for the training and holdout data are 0.32 and 0.50 standard pH units, respectively. Data generated during this study and the model output are available from the companion data release.

Alabama, Arkansas, Louisiana, Mississippi, Missour↗
USGS2025

Approximate inland extent of saltwater intrusion at the base of the Biscayne aquifer, Miami-Dade County, Florida, 2022

Miami-Dade County is part of a densely populated urban corridor in southeastern Florida. The Biscayne aquifer serves as Miami-Dade County’s primary drinking water source and is characterized by highly permeable karstic limestone and carbonate sand. The aquifer’s coastal location and permeable nature make it susceptible to saltwater intrusion. Monitoring the current inland extent and the rate of movement of the saltwater front in the aquifer can inform management strategies for conserving the long-term sustainability of the county’s water supply. In the 1950s, the U.S. Geological Survey published a map of the inland extent of saltwater intrusion in the Biscayne aquifer and has continued to update this map to monitor changes over time, with the most recent update published in 2018. An updated map has been created showing the approximate inland extent of saltwater intrusion in the Biscayne aquifer in eastern Miami-Dade County in 2022, with the 2018 extent shown for comparison. The inland extent of saltwater intrusion was mapped through the interpretation of borehole electromagnetic induction logs and measurements of chloride and specific conductance in groundwater samples. The location of the saltwater interface at the base of the Biscayne aquifer was represented by the 1,000-milligram-per-liter isochlor. This report describes changes in the location of the saltwater interface from 2018 to 2022. By 2022, the saltwater interface had moved farther inland in both the northern and southern parts of the county, advancing by as much as 0.3 kilometer in the north and up to 0.8 kilometer in the Model Land Area to the south. However, it remained relatively unchanged from its 2018 position in the east-central part of the county.

Florida↗
USGS2009

Estimating Locations of Perennial Streams in Idaho Using a Generalized Least-Squares Regression Model of 7-Day, 2-Year Low Flows

Many State and Federal agencies use information regarding the locations of streams having intermittent or perennial flow when making management and regulatory decisions. For example, the application of some Idaho water quality standards depends on whether streams are intermittent. Idaho Administrative Code defines an intermittent stream as one having a 7-day, 2-year low flow (7Q2) less than 0.1 ft3/s. However, there is a general recognition that the cartographic representation of perennial/intermittent status of streams on U.S. Geological Survey (USGS) topographic maps is not as accurate or consistent as desirable from one map to another, which makes broad management and regulatory assessments difficult and inconsistent. To help resolve this problem, the USGS has developed a methodology for predicting the locations of perennial streams based on regional generalized least-squares (GLS) regression equations for Idaho streams for the 7Q2 low-flow statistic. Using these regression equations, the 7Q2 streamflow may be estimated for naturally flowing streams in most areas in Idaho. The use of these equations in conjunction with a geographic information system (GIS) technique known as weighted flow accumulation allows for an automated and continuous estimation of 7Q2 streamflow at all points along stream reaches. The USGS has developed a GIS-based map of the locations of streams in Idaho with perennial flow based on a 7Q2 of 0.1 ft3/s and a transition zone of plus or minus 1 standard error. Idaho State cooperators plan to use this information to make regulatory and water-quality management decisions. Originally, 7Q2 equations were developed for eight regions of similar hydrologic characteristics in the study area, using long-term data from 234 streamflow-gaging stations. Equations in five of the regions were revised based on spatial patterns observed in the initial perennial streams map and unrealistic behavior of the equations in extrapolation. The standard errors of prediction for the final equations ranged from a minimum of +75.0 to -42.9 percent in the central part of the study area to a maximum of +277 to -73.5 percent in the southern part of the study area. The equations are applicable only to unregulated, naturally-flowing streams and may produce unreliable results outside the range of explanatory variables used for equation development. Extrapolation outside the range of available data was necessary, however, to predict perennial flow initiation points and transition zones along stream reaches. The map of perennial streams was evaluated by comparing predicted stream classifications with four independent datasets, including field observations by other government agencies. Overall, 81 percent of the comparison data points agreed with the USGS perennial streams model. Regions with the highest number of disagreements had a high percentage of mountainous and forested area with potential mountain front recharge zones, and regions with the highest agreements had a high percentage of low gradient, low elevation area. As a whole, the USGS model predicted a higher number of perennial streams than predictions made with the independent datasets. Some disagreements were due to poor site location coordinates, timing of the comparison site visits during unusually wet or dry years, discrepancies in classification criteria, and variable ground water contributions to flow in some areas. The Idaho Department of Environmental Quality Beneficial Use Reconnaissance Program (BURP) dataset is considered the most representative dataset for comparison because it covered a range of climate conditions and the number of sites visited were consistent from year to year during the study period. Eighty-five percent of BURP comparison data points agreed with the USGS perennial streams model. Although site-specific flow data may be needed to correctly classify streams in some areas, this information rarely is available and is not always practical to o

Scientific Investigations Report↗